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题名: 粒状分子筛催化剂Ce-MCM-48在臭氧化过程中削减溴酸根生成的中试研究
作者: 曹逢琳
学位类别: 硕士
答辩日期: 2012
授予单位: 中国科学院研究生院
授予地点: 北京
导师: 强志民
关键词: 溴酸盐生成 ; bromate formation ; 催化臭氧化 ; catalytic ozonation ; 颗粒状Ce-MCM-48 ; granular Ce-MCM-48 ; 水处理 ; water treatment ; 中试 ; pilot-scale
其他题名: Effective inhibition of bromate formation with a granular molecular sieve catalyst Ce-MCM-48 during ozonation:A pilot-scale study
中文摘要:       臭氧氧化技术在饮用水处理领域应用十分广泛,但当水源中含有溴离子(Br-)时,臭氧(O3)会将其氧化生成一种潜在致癌物质溴酸根(BrO3-)。目前国内外对BrO3-控制方法的研究大都停留在实验室阶段。课题组前期研究证明,多相催化臭氧化法可以有效削减BrO3-的生成量。 本文合成了一种颗粒状含铈(Ce)分子筛催化剂Ce-MCM-48,对该催化剂进行了结构表征,并针对其削减饮用水臭氧化过程中BrO3-生成势的效能展开了中试研究。中试采用填充有颗粒状Ce-MCM-48的升流式反应柱对含溴水进行催化臭氧化处理,分别研究了不同Br-初始浓度、水相O3浓度、总有机碳(TOC)含量、pH和水力停留时间(HRT)条件下,颗粒状Ce-MCM-48对BrO3-生成势的削减效果以及长期运行情况,同时考察了该催化剂对TOC的去除能力与对大肠杆菌的灭活效果。结果表明在常规饮用水处理条件下([O3]o = 2.0 ± 0.1 mg/L,HRT = 10 min,pH = 7.7–7.9,水温 = 18 ± 2 °C),当Br-初始浓度为200、400、800 mg/L时,该催化剂对BrO3-生成量的削减效率分别达到82.1%、90.4%、87.9%;催化剂可在较高水相O3浓度(3.5 mg/L)条件下维持对BrO3-的高效削减(﹥85%);水中TOC浓度(2.5–8.5 mg/L)、pH(6.0–9.0)以及HRT的变化(10–20 min)对催化臭氧化的BrO3-削减效果影响较小。与单独臭氧化相比,催化臭氧化对有机物的去除能力和大肠杆菌的灭活效果并未降低。长期运行结果显示:在Br-初始浓度为200 ± 20 mg/L,水相O3浓度为2.0 ± 0.1 mg/L时,设备连续运行约一个月,出水BrO3-浓度均低于10 mg/L(平均削减率达75.1%),满足国家生活饮用水标准的限值要求(GB 5749-2006)。 机理研究结果显示:颗粒状Ce-MCM-48对Br-、次溴酸(HOBr/OBr-)以及BrO3-几乎没有吸附作用;催化臭氧化可以加速水相O3的分解以生成更多的羟基自由基(•OH),从而抑制了O3对Br-的氧化,减少了OBr-的生成,使整个BrO3-生成停止在初始步骤。虽然催化臭氧化过程中生成了更多的•OH 与过氧化氢(H2O2),但这两种次生氧化剂在BrO3-生成中所起的作用很小(<10%)。 最后,对颗粒状Ce-MCM-48催化臭氧化削减溴酸根生成技术进行了经济评价。该催化剂不仅削减效率高,而且处理容量大(2.4 m3水/kg催化剂),兼以安装运行成本较低,使得总处理成本为0.09–0.14 元/L,适用于瓶装水生产领域。
英文摘要:
      Ozone (O3) has been commonly used in drinking water treatment. However, if the source water contains bromide (Br-), the application of O3 may be largely restricted due to the formation of bromate (BrO3-), a potential carcinogenic and nephrotoxic compound. Present studies about BrO3- formation control are mostly conducted in laboratory scale. The previous study of our reseach team has demonstrated that heterogeneous catalytic ozonation could effectively inhibit BrO3- formation, and meanwhile, achieved high efficiencies for dissolved organic matter (DOM) removal and bacteria inactivation. In this study, a novel granular cerium-doped molecular sieve (Ce-MCM-48) was synthesized and characterized. The inhibition efficiency of BrO3- formation during ozonation with this granular catalyst was investigated at pilot-scale under simulated practical conditions by varying the initial bromide Br- concentration, aqueous O3 concentration, total organic carbon (TOC) content, water pH, and hydraulic retention time (HRT). The efficiencies for TOC removal and Escherichia coli inactivation by catalytic ozonation were also examined. Results indicate that the inhibition efficiency of Ce-MCM-48 for BrO3- formation could reach 82-90% as the initial Br- concentration varied from 200 to 800 mg/L under typical water treatment conditions: [O3]o = 2.0 ± 0.1 mg/L, HRT = 10 min, pH = 7.7–7.9, T = 18 ± 2 °C. This catalyst could maintain an inhibition efficiency of > 85% even at a high aqueous O3 concentration (i.e., 3.5 mg/L), and the variations of initial TOC concentration (2.5–8.5 mg/L), pH (6.0–9.0), and HRT (10–20 min) had insignificant influence on the inhibition efficiency of BrO3- formation. Compared with ozonation alone, the catalytic ozonation with Ce-MCM-48 could achieve almost the same efficiencies for TOC removal and Escherichia coli inactivation. A long-term continuous experiment was operated for about one month at an intial Br- concentration of 200 ± 20 mg/L and an aqueous ozone concentration of 2.0 ± 0.1 mg/L. for one month Results indicate that the effluent BrO3- concnetration was always below 10 mg/L (average inhibition efficiency = 75.1%), which met the requirement of the Chinese Standards for Drinking Water Quality (GB 5749-2006). The mechanism study showed that that the granular Ce-MCM-48 had little adsorption of BrO3-, Br- and HOBr. Compared with ozonation alone, catalytic ozonation accelerated the decomposition of aqueous ozone to hydroxyl radical (•OH), and thus inhibited the oxidation of Br- to OBr- by molecular ozone. As a result, the formation of BrO3- was terminated at the intial reaction stage. Although the catalytic ozonation generated more •OH and hydrogen peroxide (H2O2), thecontribution of the two generated secondary oxidants to BrO3- formation was relatively insignificant (< 10%). Finally, economic assessment was performed regarding the practical application of the catalytic ozonation process (O3/Ce-MCM-48) for inhibiting BrO3- formation. Results indicate that the catalyst possesses not only a high inhibition efficiency but also a large treatment capacity (i.e., 2.4 m3 water/kg catalyst). In addition, the equipments installation and operation costs are relatively low. The total treatment cost is estimated to be 0.09–0.14 yuan/L, thus has promising applications to bottled water production industry.
内容类型: 学位论文
URI标识: http://ir.rcees.ac.cn/handle/311016/35118
Appears in Collections:环境水质学国家重点实验室_学位论文

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Recommended Citation:
曹逢琳. 粒状分子筛催化剂Ce-MCM-48在臭氧化过程中削减溴酸根生成的中试研究[D]. 北京. 中国科学院研究生院. 2012.
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